1. Field of the Invention
The invention relates generally to balers of the type forming cylindrical bales between powered belts and, more particularly, to an improved bale-forming system and a power drive therefor.
2. Prior Art
U.S. Pat. No. 3,722,197 shows a baler for large cylindrical bales formed between a lower belt 21 and a plurality of upper belts 51. The belts 51 are trained on a plurality of rollers journalled on an upright frame structure 26 which includes a pivoted frame section 28. The section 28 is pivotable rearwardly about connection 38 during bale formation. A roller 46 is journalled at the lower end of the section 28 in engagement with the belts 51 and defines a rear parameter of the bale-forming zone between the belts. As the section 28 pivots rearwardly during bale formation it will be seen that the roller 46 will move through an arcuate path defined about the pivot connection 38. This results in increasing the space between the roller 46 and the belt 21 as the frame section 28 pivots toward its rearward most position as the bale approaches full size. It will be apparent that as the gap increases hay on the belt 21 can escape under the roller 46 and rearwardly out of the baler.
An attempt to solve this problem involved a modification of a baler of the type shown in U.S. Pat. No. 3,722,197. The rearmost roller 66 for the belt 21 was movably mounted and interconnected to the lower mounts of the cylinders 89. As the frame 28 was swung forwardly the contraction of the cylinders 89 moved the cylinder mounts upwardly after the frame section 28 reached its full forward position. Due to the mechanical interconnection between the cylinder mounts and the roller 66, the roller was caused to shift upwardly. Thus, in theory, the lower belt was disposed upwardly at a position more closely contiguous to the arcuate path of movement of the roller 46. In practice however, the upward shift of the roller 66 lifted the belt 21 off the next adjacent roller 68. As the incoming hay was collected on the belt during baling the belt was pressed back down onto the roller 68. The actual path of movement of the running belt 21 was never truly arcuate, and moreover, was actually changed during the baling process. And this changed the space between the belt 21 and the arcuate path of the roller 46. Thus, it was impossible to create a uniform close spacing between the lower belt 21 and the upper belts 51 throughout the rearward arc of movement of the roller 46.
The above-mentioned patent shows a power drive system (FIG. 7) for the pickup, lower belt, feed roll, and upper belts. It will be noted that the upper belts 51 are driven through three rollers 41, 44, and 45 by a continuous drive chain 127 trained on respective drive sprockets 132, 134, and 133. Since the baler is designed to produce bales having diameters of up to seven feet, the chain 127 must be of considerable overall length to extend to the top of the baler to drive the uppermost rollers 44 and 45. Of course, the cost of materials increases with increased linear extent of the drive system. More importantly, considerations of safety require that every reasonable attempt be made to enclose or shield the drive from access during operation. A drive system which extends virtually the full height of the machine increases the difficulty and costs of designing and manufacturing the requisite shielding.
Balers of the type shown in the above-referred-to patent include a belt tension unit 56 pivoted on the frame at 59 and having a pair of rollers 53 and 54 in engagement with the upper belts 51. Hydraulic cylinder units 88 and 89 provide resistance to the upward movement of the tension unit 56 as the size of the bale increases, thus keeping the belts taut.
It will be noted that the belts 51 extend directly between the tension rollers 53 and 54 and the frame-mounted rollers 44 and 45. Due to the fact that the rollers 44 and 45 are power-driven, a problem is created as the belt tension unit moves upwardly. The effect of the upward movement is to "feed out" the belts for use in surrounding the bale as it grows in diameter. This moves the belts relative to the peripheral speed of at least one of the power-driven rollers 44 and 45. Accordingly, the belts slip on the power-driven rollers and are subject to premature wear.